System and method for the microscopic generation of object images

ABSTRACT

A method is disclosed for mixing pairs of confocal images and different arrangements for fast generation of parallel confocal images and the combination thereof in real time. The method is used for improving contrast and resolution in confocal images. The suggested arrangements point to some possibilities for a meaningful application of the method for image mixing in parallel confocal single-beam or double-beam methods for the generation of highly resolved images in real time for a wide variety of different applications, especially also for material inspection. By combining at least two confocal images, a resolution of the fine structure of the object is achieved in the mixed image. Contrast, lateral resolution and depth resolution are improved in the mixed image of the object to be examined, which can also be a phase object. Further, the method permits the generation of very highly resolved three-dimensional digital images of optical objects to be examined.

BACKGROUND OF THE INVENTION

Field of the Invention

The invention relates to an arrangement and method for generating objectimages in a microscope. In particular, a method for mixing pairs ofconfocal images and different arrangements for fast generation ofparallel confocal images and the combination thereof in real time. Themethod is used for improving contrast and resolution in confocal images.The suggested arrangements point to some possibilities for a meaningfulapplication of the method for image mixing in parallel confocalsingle-beam or double-beam methods for the generation of highly resolvedimages in real time for a wide variety of different applications,especially also for material inspection. By combining at least twoconfocal images, a resolution of the fine structure of the object isachieved in the mixed image. Contrast, lateral resolution and depthresolution are improved in the mixed image of the object to be examined,which can also be a phase object. Further, the method permits thegeneration of very highly resolved three-dimensional digital images ofoptical objects to be examined.

Description of the Related Art

The following references may be pertinent to the present invention:

Patents DE 4023650 A1 7/25/1990 Dodt DE P 40 35 799.6 11/10/1990Groβkopf, et al. WO 92/01965 7/8/1992 Wijnaendts DE 4429416 A1 8/19/1994Velzel, et al. DE 19511937 C2 3/31/1995 Schöppe DE 19529546 A1 8/11/1995Kapitza DE 19627568 A1 7/9/1996 Czarnetzki DE 19632594 A1 8/13/1996Schwider 19714221.4 2/12/1997 Ott, et al. WO 97/31282 8/28/1997 Wilson,et al. US 5264912 US 5365084

Literature

“Image Formation in the Scanning Microscope,” C. J. R. Sheppard, A.Choudhury; Optica Acta, 1977, Vol. 24, No. 10, pages 1051-1073.

BRIEF DESCRIPTION

Aside from confocal laser scanning microscopes which often only permit avery complicated and lengthy building of the image, arrangements havebecome established, above all, for scanning an object plane underexamination by means of Nipkow disks, or various scanning pinhole arrays(DE P 4035799.6, DE 19627568 A1, 19714221.4) have been suggested forgenerating confocal images. In addition to typical incident or reflectedlight arrangements, transmitted light arrangements have also beensuggested (DE 4023650 A1) which have not yet been realizedtechnologically. All of these forms of scanner with confocal bundlesoperating simultaneously (in parallel) have the advantage of fastconfocal image formation in real time for high-contrast observation withthe naked eye as well as with a camera (WO 92/01965). In this last citedpatent, the camera is used as a surface receiver with confocal featuresthrough sensitivity control of surface elements; however, the completeimage is built very slowly by the required joining together of partialimages. Generally, the disadvantages of parallel confocal single-diskscanners are the poor illumination efficiency (low percentage) andlimited confocality due to crosstalk effects of the parallel channels.Improvements in the illumination efficiency were achieved influorescence applications through the use of combinations of micro-opticcomponents with coincident pinhole arrays (EP 0539691 A2, DE 19627568A1).

Parallel confocal arrangements have the problem of a highly illuminatedimage background which is caused by reflections or scattering at thepinhole disk and which can easily cover up the actual image content. Inorder to reduce the disruptive scattered light influence of anindividual Nipkow disk, Xiao and Kino, et al., 1987, suggested aninclined disk with a directed-reflection disk surface whose illuminationreflections and back-reflections were masked in a controlled manner. Thesteps for eliminating interfering light were supplemented in DE 19511937C2 by optical wedges and rhombic cut splitter elements above a Nipkowdisk and therefore by a more thorough elimination of destructive lightcomponents in the image bundle. Some of the disturbances of the confocaleffect in the main beam path which occur as a result of added elementscan be accepted in many applications, but not often in the use ofconfocal microscopes in applications demanding very high quality, e.g.,in microbiology or inspection technology. An enormous improvement in thesuppression of false light was achieved by physically separating theconfocal elements in illumination from those in confocal observation.Unfortunately, the resulting use of two confocal arrays also caused anintensified sensitivity in the production of the necessary exactconjugation (19714221.4).

In WO 97/31282, a form of masking correction is carried out in confocalimages in that a bright-field image is combined with a confocal image byjoint exposure on a camera and subsequent subtraction with a purebright-field image of the same object section. This results in abrighter image on the camera, which, among other things, is supposed tocompensate for general deficiencies in illumination of the confocalimage to nonconfocal microscope images.

U.S. Pat. No. 5,365,084 describes an arrangement for examining a runningstrip of web with a TDI sensor for light detection. The use of a CCDarray or a TDI sensor for wafer inspection is provided in U.S. Pat. No.5,264,912.

OBJECT AND SUMMARY OF THE INVENTION

The primary object of the invention is to increase contrast andresolution of confocally recorded images. This object is met in anarrangement for generating object images in a microscope, comprisingmeans for recording at least two confocal images of the same object withdistinguishable optical object information with respect to image pixelsand for storing them one after the other, and means for combining therecorded and digitized images in a pixel-exact manner, and for storingthe mixed image formed in this way.

The object of the invention is to further improve the contrast andresolution of confocal images with the possibility of fastthree-dimensional imaging of transparent objects or surfaces havingvertical structure by applying an image mixing method accomplished bymeans of combining different confocal images of an object section andrepresenting them electronically (in real time). The description relatesto the method for mixing confocal images and to different arrangementsfor fast generation of parallel confocal images and suitable combinationthereof in quasi-real time. However, the mixing method is alsoapplicable to any form of confocal images which can image exactly thesame object section, e.g., also suitably generated images from laserscanning microscopes. However, within the framework of the presentdescription, parallel confocal embodiment forms are discussed mainly.

Parallel confocal illumination rasters and imaging rasters for fastgeneration of confocal, electronic images with complete imageinformation are generated and stored for the subsequent imagecombination using different scanning principles. The total image isbuilt very quickly through the parallel-acting generation of confocalimage points in the partial beam paths. The speed of the imagecomposition offers favorable base conditions for the decoupling ofthermal or mechanical disturbances (vibrations) during the building ofthe image. It also offers the possibility of generating a quasi-realtime image which also permits process examinations in or on the objectunder examination. Due to the efficiency of the image formation and theadvantageous depth discrimination of the special confocal principle, 3-Dimages can also be generated and can supply new object informationespecially with transparent objects (phase objects).

The invention will be described more fully in the following withreference to the schematic drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIGS. 1a(A) and 1 a(B) show an arrangement for a parallel confocal imagemixing process with a modified Nipkow disk;

FIG. 1b shows a modified Nipkow disk for parallel confocal image mixingmethods;

FIGS. 2A and 2B are a schematic representation of the image pointcorrelations in the image mixing process;

FIGS. 3A and 3B show an arrangement for a parallel confocal image mixingmethod with a modified strip scanner;

FIG. 4 shows a detail of a modified strip scanner for an image mixingmethod;

FIG. 5 shows variants of the rhombic arrangement on strip scanners for aconfocal image mixing method;

FIG. 6 shows additional variants for generalized pinhole elements;

FIGS. 7A and 7B show an arrangement for a parallel confocal image mixingprocess with a Nipkow disk and two illumination wavelengths;

FIG. 8 shows examples for other generalized pinhole types;

FIGS. 9A and 9B show an arrangement for a parallel confocal image mixingprocess realized as a construction with two bundles and the linearscanning principle;

FIGS. 10A and 10B show an arrangement for a parallel confocal imagemixing method as a construction with mono-bundle and linear scanningprinciple; and

FIGS. 11A and 11B show an arrangement for a parallel confocal imagemixing method with two lasers for illumination as single-beamconstruction with two TDI cameras using the linear scanning principle.

DESCRIPTION OF THE PREFERRED EMBODIMENT

In FIG. 1a, a white light source WQ, field diaphragm LBL, collector lensKL, aperture stop ABL, mirror S1, condenser lens KOL, exchangeabledichroic beam splitters ST1, ST2, ST3, and a carrier disk TS withdifferent ring sectors with pinhole arrays PH1, PH2 are arrangedsuccessively in the illumination beam path. A pulse sensor IS detectsthe passage of pulse markers IM1, IM2 which are arranged on the carrierdisk TS and which are allocated to the ring sectors.

The illumination of the object O in the object plane is carried out bytube lens TUL and imaging objective AO1. The light coming from object Opasses via a selectable beam splitter ST and magnifying detector opticsDL, arriving at a camera KA which can be a CCD matrix camera. Theanalog-to-digital converter AD, frame grabber FG, storage SP1, SP2, andprocessor PR, which can be component parts of a computer PC in which themixed image MB originates, are necessary electronic and softwarecomponents which are arranged successively in a typical manner for sucha process.

The first main version of a scanner for the image mixing process is amodified Nipkow-type pinhole disk. In a first variant, different ringsectors with various pinholes or perforated elements which can beselected as squares, rhombuses or ring elements such as perforatedrings, square rings or the like are structured on the Nipkow disk withsuitable spiral patterns which have different element sizes and spacingin the ring sectors of the rotating disk. The pinhole elements or theentire structure of the ring sectors as well as the synchronizing andtiming tracks are produced by a microlithography structuring process,for example. Because of the rotating movement of the Nipkow disk, thereis a cycling or periodic recurrence of different ring sectors of thedisk in the radiant field/intermediate image plane. They are marked attheir start and at their end by synchronizing markers outside thepinhole zone and are read by an electronic auxiliary sensor during therotation of the pinhole disk and are used in turn as a synchronizingsignal.

The individual markers differ from one another, for example, as singlemarkers and double markers, in order to ensure an unambiguous readout ofthe disk position.

The entire arrangement for realizing the image mixing process with thismodified Nipkow scanner will be described in the following withreference to FIG. 1a. The basic optical arrangement comprises amicroscope with the modified Nipkow disk as confocal element. Anincoherent conventional light source is used for illumination. One or,depending on the application, more exchangeable splitter elements fordividing the illumination beam path from the imaging beam path areformed either as neutral splitters, dichroic splitters or as polarizingsplitters. The Nipkow disk rotates vertical to the optical axis at theheight of the intermediate image plane in the microscope. A secondaryimage of the object under observation is generated on the receiver KA bythe after-magnifying detector optics DL. The rate of rotation of themodified Nipkow disk should be capable of regulation in order to be ableto adapt to the intensity ratios of different observation objects duringexposure of the receiver. The modified Nipkow disk causes a confocalimage type 1 to originate in ring sector PH 1 and, after furtherrotation of the disk, causes a confocal image type 2 to be formed inring sector PH2. Both image types are again recorded one after the otherwith respect to time by the surface receiver KA and distinguishablydigitized by an A-D-converter arranged downstream.

FIG. 1b shows the basic construction of the modified Nipkow disk and thepinhole structure schematically as well as its sector configuration. Thecarrier disk TS in FIG. 1b is provided with pulse markers IM on a timingtrack TKS and with different pinhole zones PH1, PH2, black zones SZ1,SZ2 and a centering circle ZK. The modified Nipkow disk is thereforeformed of two ring sectors with different, generalized pinholeelements—separated by dark regions—with a spiral-shaped basicarrangement of the pinholes relative to one another in order to achievethe confocal scan of the entire object surface (in the radiantfield/intermediate image plane) through the rotating movement of theNipkow disk. Each of the pinhole elements of a ring sector has the samecharacter (geometry, pinhole area) and average distance from oneanother; the coverage with the pinhole area should preferably beidentical in the two ring sectors. Corresponding to the actual spiralstructure, an image is completely scanned after a certain rotationalangle of the Nipkow disk, wherein a multiple quantity of scanningprocesses of an object region should take place per ring sector toprevent defects during the scan (wobbling of disk, eccentric running ofthe disk) by averaging the occurring optical image sequences, amongothers. The spiral pattern can be arranged so as to rotate in theclockwise or counterclockwise direction; the disk can always rotate inany direction desired. The black sectors SZ1, SZ2 serve to divide thering sectors and to cancel (zero setting of the camera) the precedingimage.

The process for improving confocal images includes the combining of atleast two or more confocal images of an identical observation object oran identical object section. For practical conversion, the confocalimages to be mixed are optically generated in very quick succession oneafter the other and then combined electronically in a picturepoint-exact manner. By picture point-exact is meant, for example, foreach individual pixel of a CCD camera or TDI camera. The operations forcombining aim at an improvement in the quality and resolution of themixed image. There is an improvement in contrast, lateral and depthresolution in the mixed image as a reproduction and information carrierof the real object to be examined. This is achieved by means of picturepoint-oriented combination operations such as displacement operations,multiplicative or differential operators of and with the image pixels orpixel information originating from the receiver. The most important andessential combination operations Δ(P_(ij)) of the image pixel matricesis the subtractive operation with the confocal image pair which isdefined mathematically by the following formula:

Δ(P _(i″j″))≡P _(i″j″) =P _(ij) −P _(i′j′)  (1)

P_(i″j″) resultant elements of the image matrix after combination

P_(ij) pixel elements of confocal image matrix 1

P_(i′j′) pixel elements of confocal image matrix 2

The basic procedure will be illustrated by way of example of 9×9 pixelelements of the image matrices in FIG. 2. FIG. 2 shows the two recordedimage pixel matrices BM1, BM2 which are stored in SP1, SP2 and the mixedimage matrix MBM which is formed by the above signal processing andstored. With an exact spatial agreement between the object regions inthe two confocal initial images with different confocal resolution, thenecessarily digitized image pixels can be formed immediatelymathematically by subtraction of the correlated line elements (identicaluppercase letters) and column elements (identical lowercase letters) ofthe image matrices. Exact spatial agreement means that the imagingconditions and the object position do not change during the successiverecordings, which can be achieved in particular by known steps such asvibration damping. The method can be applied for confocal reflectedlight images as well as confocal fluorescence images, but, of course,with very different results in the possible final resolution in themixed image, since the interaction between the confocal optic sensingprobe and the object to be imaged in fluorescence applications containsno scatter components, but rather is determined by the self-luminouscharacter of the object.

With respect to apparatus, conversion is preferably carried outoptically with types of scanners that can generate two differentconfocal images very quickly. The synchronization with the receiver withrespect to time is carried out in two embodiment versions viasynchronizing tracks on the Nipkow scanner, as is shown in FIG. 1a, or astrip scanner, as is shown in FIG. 3, or on a filter wheel, as is shownin FIG. 7, which are electrically connected with the receiver viasensors. In a third scanner version, two confocal images are formed atthe same time by the use of two cameras, as is shown in FIGS. 9 and 10,wherein the object sections which are currently being scanned differfrom one another spatially through the progressive scanning, but at alater point in time have imaged the same object portions. In aparticularly advantageous arrangement, temporal and spatial separationof the two confocal images are eliminated, which is shown schematicallyin FIG. 11. The two confocal images or multiple pairs of confocal imagesof the object under examination are digitized for further processing andare detected separately in a framegrabbing process in storages. Thesynchronizing signals supply the distinguishing criterion for thestorage of the different images. When at least two images are stored,the combination can be carried out by means of the image processingprocessor (DSP). The definitive mixed image is then available forvisualization (monitor, image printer, image evaluation, or the like).

FIG. 3 shows the arrangement for realizing the image mixing process witha strip scanner. Aside from the reference numbers analogous to FIG. 1,FIG. 3 shows a carrier strip TB with a motor-driven driving disk AS andanother running disk LS, wherein AS, LS are articulated so as to berotatable in a stationary manner, which is not shown. In this case,also, pulse markers IM3 are provided on the strip TB for detecting thestrip position. In FIG. 3, the basic optical arrangement is a microscopewith a modified strip scanner as confocal element. Again, a conventionallight source (continuous or line-source) is used for illumination inorder to counter troublesome interference effects or speckle. Köhlerillumination, which is well-known, is applied to achieve anadvantageously uniform illumination over the field. One or, depending onthe application, more exchangeable splitter elements which are intendedto divide the illumination beam path from the imaging beam path can beformed as neutral splitters, dichroic splitters or polarizing splitters.The confocal strip, which, as was already mentioned, is provided withdifferent generalized pinhole structures in different strip zones,revolves at right angles to the optical axis at the height of theintermediate image plane in the microscope, wherein some opticalelements of the microscope beam path must be orbited by the stripdepending on circumstances. In the present case, these elements are thesplitters ST1-3, lens KOL and mirror S1. The strip can run over drivingrollers or deflecting pulleys and should be able to be regulated withrespect to revolving speed so as to be able to adapt to the intensityratios of different observation objects during the exposure of thereceiver. By means of the confocal strip, a confocal image type 1 isformed in pinhole zone PH1 and, after the strip advances, a confocalimage type 2 is formed in pinhole zone PH2.

Pinhole elements going beyond the depicted circular pinhole geometry canbe structured on the strip as confocal stops. This is shown in FIG. 5.

The two image types are recorded one after the other in time by asurface receiver and distinguishably digitized by an A-D converterarranged downstream. The image types are distinguished by means of thesynchronizing pulses IM3 which are arranged on the scanner strip formarking the pinhole zones and which are recorded by an auxiliary sensoras is shown in FIG. 1. They are used for controlling the camera(sensitivity circuit, electronic gating), for the correct choice ofimage storages for the respective confocal image types, and for thesoftware triggering of the time point of meaningful combination of thestorage contents by the image processor to form the mixed image.

FIG. 4 shows a section of the carrier strip TB with pulse markers IM3 onthe timing track TS and portions of the carrier strip TB with pinholearrangements PH1, PH2. This form of scanner for the image mixing processis based on a revolving pinhole strip. Areas with pinholes or moregeneral pinhole elements such as squares, rhombuses or ring elementssuch as perforated rings, square rings or the like which have differentelement dimensions and spacing in various zones of the strip arestructured on or in a flexible material, e.g., a thin steel strip, aplastic material or a film strip capable of blackening. These elementscould have been shaped and etched, e.g., by a microlithography exposureprocess, or may have been generated by a photochemical exposure processas a periodic pattern. The different pinhole element zones of the striprecur periodically and are marked by markers outside of the pinholeelement zone at the start of the strip and read by an electronic sensorwhile the strip runs and are used as a synchronizing signal.

The strip is generated as a periodic pattern and, finally, is joinedtogether in a suitable length to form a closed strip (by gluing).

The confocal strip in FIG. 4 comprises two different pinhole zones witha principally rhombic basic arrangement of the pinholes relative to oneanother in order to accomplish the scan for the entire object surfacethrough the running of the strip. The pinholes of a pinhole zone havethe same geometry and spacing relative to one another, wherein coveragewith pinhole area should be identical in both pinhole zones.Corresponding to the spacing of the basic rhombic raster, an image iscompletely scanned after a determined running length of strip; acomplete quantity of periodic structures should be present per pinholezone. This results in a different length of pinhole regions and imagebuilding time, but, nevertheless, in the same average exposure intensityfor building the two confocal image types. But this has a positiveeffect on the control of the receiver for the exposure of the twoconfocal image types.

The arrangement for the pinhole geometry can be right-handed orleft-handed, as desired, as is shown in FIG. 5. FIG. 5 shows a basicrhombic arrangement PH11, PH12 running to the left relative to thescanning direction (arrow) in 5 a, 5 b and a basic rhombic arrangementPH21, PH22 running to the right relative to the scanning direction in 5c, 5 d.

FIG. 6 shows examples of pinhole elements in the form of rhombic andcircular holes as confocal elements for a strip scanner. FIG. 6 showstwo pairs of confocal structures in left-hand basic rhombic arrangementsPH13, PH14 with rhombus-shaped pinhole in 6 a, 6 b and right-hand basicrhombic arrangements PH23, PH24 with a circular pinhole shape in 6 c, 6d.

Another advantageous scanner variant with a simple Nipkow disk is shownin FIG. 7. Aside from the elements already mentioned, it shows amotor-driven filter wheel FD with color filters FF1, FF2 for wavelengthsλ1, λ2 and the carrier disk TS with a uniform pinhole pattern PH3.Analogous to Fire 1, a conventional white light source is used asillumination. The splitter element ST is preferably formed as a neutralsplitter. The Nipkow disk also rotates at the height of the intermediateimage plane in the microscope, but is only structured with one pinholetype. The different confocal images are formed in this arrangement byprocessing according to the method, already described, as images withdifferent color information of the same observation object. The rate ofrotation of the color filter disk used according to the invention shouldbe capable of regulation to be able to adapt to the intensity ratios ofdifferent observation objects during the exposure of the receiver.Depending on the actual illumination wavelength, the Nipkow disk causesa confocal image type 1 to be formed or, after switching or furtherrotation of the color filter disk, a confocal image type 2. Byexchanging the filter disk FD, other wavelengths can be used.Distinguishing between the image types is carried out by means of thesynchronizing pulses IM4 which are applied to the color filter sectorsand recorded by an auxiliary sensor. They are used in turn to controlthe camera (sensitivity circuit, electronic gating) as well as for thecorrect choice of image storages for the respective confocal image typesand for the software triggering of the time point of meaningfulcombination of the storage contents by the image processor to form themixed image.

FIG. 8 shows two examples for pairs of pinhole elements on a modifiedNipkow disk in the form of hexagonal pinholes and square ring pinholesas confocal elements arranged in Nipkow-type spiral structures insections. FIGS. 8a, 8 b show a spiral structure with hexagonal pinholetype PH1, PH2 and FIGS. 8c, 8 d show a spiral structure with squarepinhole type PH1, PH2.

FIG. 9 shows another advantageous arrangement according to the inventionwith light sources LQ1, LQ2, field diaphragms LBL1, LBL2, collectorlenses KL1, KL2, aperture stops ABL1, ABL2, mirrors S11, S12, condenserlenses KOL1, KOL2, beam splitters ST4, ST5, and carrier disk TS1, TS2which can be component parts of a common carrier disk. Tube lenses TUL1,TUL2 and imaging objectives AO2, AO3 are arranged in the direction ofthe object O. The object O is displaced in a defined and controllablemanner by means of an object translator OT. The following are providedin the direction of detection: optically after-magnifying detectionoptics DL1, DL2, cameras KA1, KA2, analog-to-digital converters AD1,AD2, framegrabbers FG1, FG2, storages SP1, SP2, and a processor PR forgenerating the mixed image MB.

This third basic version of a scanner for the image mixing process is alinear scanner with rhombic arrangement of the confocal elementsrelative to one another and can be used in a mono-bundle or dual-bundlearrangement. Two zones which are suitably offset spatially relative toone another are located on the stationary disk with the confocalelements (pinhole elements), these two zones having pinhole elements(right-angled) with a basic rhombic pattern of pinhole elements relativeto one another and different sizes of pinhole elements and averagespacing in the respective pinhole zone. The pinhole elements in thedifferent zones and the correct position of the regions relative to oneanother are designed and structured very exactly relative to oneanother, e.g., by a microlithographic production process. With thelinear scanning principle, a section of the object under observation isscanned in a parallel confocal manner and its (line) image is completelygenerated through uniform displacement of the observationobject—relatively similar to the scanning action in the strip scanner bycirculation of the strip—within a displacement path depending on thebasic rhombic structure. However, the confocal image can advantageouslybe electronically evaluated efficiently only by means of a specialcamera (TDI camera) which unifies the “confocal point pattern image” bymeans of its operating principle of synchronous transverse displacementof the photoelectronically generated charges between the parallelizedlines (stages) to form a closed line image. Finally, the line image isread out very quickly and continuously, so that a stripe-shaped imageformat of the observation object is formed during the movement of thelatter.

The linear scanner suggested above can be applied in an optical basicarrangement similar to a microscope (automatic inspection machine). Inthis case, the light sources can be two conventional lamps (preferablyshort-arc lamps) or two different lasers which, in sub-variants of thearrangement, can be operated with different wavelengths or with the samewavelengths. Two splitter elements (also exchangeable by pairs) whichare intended to divide the illumination beam path from the imaging beampath are formed either as neutral splitters, dichroic splitters or aspolarizing splitters.

The object under observation (primarily wafers in the structuringprocess) is moved uniformly at right angles to the optical axis of theoptical arrangement, so that the parallel confocal image scan is carriedout at the height of the intermediate image plane of the device by meansof the basic rhombic pattern of the pinhole elements relative to oneanother. The speed of displacement of the object under observationshould be capable of regulation in order to be able to adapt to thesensitivity (exposure, light density source) as well as to the readoutspeed of the receivers (TDI line cameras). The linear scanner causes aconfocal image type 1 (with elongated image format) to be formed inpinhole zone 1 or a confocal image type 2 (likewise with elongated imageformat) to be formed in a spatially offset manner in pinhole zone 2.Every image is recorded simultaneously—in this instance in an opticallyparallel manner, but so as to be slightly offset spatially—by theassociated receiver and is digitized by an A-D converter arrangeddownstream. The receivers should advantageously be TDI (Time DelayedIntegration) line cameras which have extremely high readout rates andaccordingly permit an efficient, continuous object movement andtherefore achieve the highest testing productivity currently attainable.The distinguishing of the image types (storage) is obviously simple inthis third basic version of the scanner. The exactly known spatialseparation of the two image bundles and the object speed enable thecorrelation of identical object structures (in a pixel-exact manner) inthe images and the electronic representatives thereof in the storagesfor the image mixing. The meaningful combination of storage contents bythe image processor for the mixed image can accordingly be carried outwhen digital image components of the respective identical object sectionare present. Determination of the exactly identical image section iscarried out by means of the known displacement speed and constantspacing of the pinhole zones.

FIG. 10 shows another advantageous variant of the linear scanner whichis simpler to adjust and more stable and which uses only one opticalimaging system, but two confocal bundles. In this case, the bundles aremoved close together, for example, by means of narrower beam splitters.Apart from the elements already mentioned, FIG. 10 shows a tube lensTUL3 common to both beam paths, a common imaging objective AO4 andoptically after-magnifying detection optics DL3.

In this arrangement, only one imaging optical system is used, which isonly possible with suitably corrected large optical work fields of thetransmission system.

The decisive advantage in this case is the more compact construction andthe small distance between the optical confocal work fields, which makesthe arrangement faster and less sensitive to disturbances (vibrations orthe like) and considerably simpler to adjust. The illumination iscarried out in the first arrangement with two conventional lamps(preferably short-arc lamps) or two different lasers.

In contrast to nonconfocal, conventional incident illumination, thespecial nature of the confocal illumination principle and imagingprinciple in the method and arrangements according to the inventionpermits the use of lasers as a light source. In conventional incidentillumination (no fluorescence application) in microscopy, the use oflasers is prohibited in general (apart from micro-interferometricarrangements, e.g., DE 19632594 A1) because the coherent secondaryeffects of the laser (speckle, disturbances caused by interferingreflections) are very strongly superimposed on the image during imaging,critically interfering with the latter. With confocal image generation,the situation is changed with regard to image formation at the objectsite: the confocal diffraction-limited “microprobe” has no interactionwith other points of the observation object while the image is beingbuilt, but only with the object point currently being scanned. Thismeans that the successively occurring image points of the object regionare completely incoherent relative to one another. This results in anincoherent character of the optical raster image and total digitalimage. The statistically occurring spatial-temporal coherence cellswhich manifest themselves as speckle in the laser bundle and which givethe phenomenological, characteristic granulation in the laser beam crosssection are eliminated or reduced by the likewise spatially-temporallyacting averaging by means of scanning over the beam cross section of theilluminating laser and accordingly prevent the granularity in the imagepoints which falsifies intensity. A further advantage of the confocalimage construction is the sharp reduction in the influence of secondaryreflections of the lens surfaces of the imaging optical system due tothe confocal stops in the image plane which allow only a fraction of theinterference-susceptible false light to penetrate into the secondaryimage space (reflection images occur, among others, remote of the imageplane in correctly designed systems) and reduce their contrast-damagingeffect in the image.

An advantage of the linear scanning principle in the suggested case ofapplication is that different mixing principles can be applied: theconfocality can be adjusted not only by changing the pinhole size, butalso, e.g., by selecting different illumination wavelengths in the twochannels or by selecting different apertures in the imaging channels.This results in advantageous combinations and additional qualitativeadvantages for conversion of the image mixing process.

FIG. 11 shows an arrangement with two lasers for illumination and twoTDI cameras in the linear scanning principle. Laser L1 with wavelengthλ1 and laser L2 with wavelength λ2 are focused pointwise via beamsplitter ST6 and condenser lens KOL3 and a microlens array MLA in thedirection of a pinhole array PH3. The illumination of the object iscarried out via tube lens TUL4, a quarter-wave plate PL and the imagingobjective AO5. A polarizing beam splitter PST is arranged between thepinhole arrangement PH3 and microlens array MLA for masking in thedirection of optically after-magnifying detection optics DL4 and adichroic beam splitter ST7 for dividing up the detection light in awavelength-selective manner in the direction of cameras KA1, KA2,followed by elements that have already been described.

This advantageous version of an automatic inspection device according tothe image mixing process with two different colored lasers forillumination means that the advantage of the laser—unsurpassed spectralluminous density—is made use of for an optimal exposure process of theTDI camera without being directly subjected to the decisive disadvantageof the laser light sources—contrast-degrading action due to the greatcapacity for interference of the lasers in optical imaging.

With laser illumination, the illumination efficiency in parallelconfocal arrangements can be enormously improved by a microlens array(conjugated to rhombic pinhole array). In the suggested version, thespecial array MLA for the image mixing process must be color-correctedwith different working wavelengths and one pinhole type for the twolaser lines and is advantageously illuminated in parallel by thecondenser.

A secondary condition which must be met consists in that the focallength and diameter of the microlenses must correspond to the requiredimage-side apertures of the optical main system and must be exactlycentered with respect to the pinhole array, so that a “criticalillumination”, as it is called, of the pinhole elements is generated.Thorough coupling (mixing together) of the two lasers in theillumination beam path is carried out by means of a dichroic mirror ST6.The separation (de-mixing) of the different colored laser images in theimaging beam path is likewise carried out by means of a dichroic mirrorST7. The separation of the illumination beam path and imaging beam pathis advantageously carried out by means of a polarizing-optical splittermirror PST in combination with a broad-band quarter-wave plate for thelaser lines.

Other mixing variants beyond the multiple-channel arrangements depictedare possible: these are, e.g., different polarizing-opticalcharacteristics of the two transmission channels which can be utilizedfor mixing. Depending on the peculiarities of the objects underobservation, these different varieties can be applied to cover up orrender visible new object characteristics.

Further, the invention can advantageously be applied to laser scanningmicroscopes such as the Zeiss LSM4 or 5 and was tested for the latter inthat a plurality of confocal reflection images of the same objectportion were recorded and processed as described above.

While the foregoing description and drawings represent the presentinvention, it will be obvious to those skilled in the art that variouschanges may be made therein without departing from the true spirit andscope of the present invention.

LIST OF REFERENCE NUMBERS

FIG. 1a

white light source WQ

field diaphragm LBL

collector lens KL

aperture stop ABL

mirror S1

condenser lens KOL

exchangeable dichroic beam splitters ST1, ST2, ST3

carrier disk TS

pinhole arrays PH1, PH2

pulse sensor IS

pulse markers IM1, IM2

tube lens TUL

imaging objective AO1

object O in object plane

detector optics DL

camera KA

analog-to-digital converter AD

framegrabber FG

storages SP1, SP2

processor PR

computer PC

mixed image MB

FIG. 1b

carrier disk TS with pulse markers IM on a timing track TKS

pinhole zones PH1, PH2

black zones SZ1, SZ2

centering circle ZK

FIG. 2

image pixel matrix BM1, BM2

mixed image matrix MBM

FIG. 3

reference numbers analogous to FIG. 1

carrier strip TB

motor-driven driving disk AS

running disk LS

AS, LS articulated in stationary manner, not shown

pulse markers IM3

FIG. 4

section of carrier strip TB

pulse markers IM3 on timing track TS

portions of carrier strip TB with pinhole arrangements PH1, PH2

FIG. 5

5 a, 5 b basic rhombic arrangement PH11, PH12 running toward left-handside relative to scanning direction

5 c, 5 d basic rhombic arrangement PH21, PH22 running toward right-handside relative to scanning direction

FIG. 6

6 a, 6 b: left-hand basic rhombic arrangements PH13, PH14 with rhombicpinhole shape

6 c, 6 d: right-hand basic rhombic arrangements PH23, PH24 with circularpinhole shape

FIG. 7

aside from elements already mentioned,

motor-driven filter wheel FD with color filters FF1, FF2 for wavelengthsλ1, λ2 carrier disk ts with a pinhole pattern PH3

FIG. 8

FIGS. 8a, 8 c: spiral structure with hexagonal pinhole type PH1, PH2

FIGS. 8b, 8 d: spiral structure with four-sided pinhole type PH1, PH2

FIG. 9

light sources LQ1, LQ2

field diaphragms LBL1, LBL2

collector lenses KL1, KL2

aperture stops ABL1, ABL2

mirrors S11, S12

condenser lenses KOL1, KOL2

beam splitters ST4, ST5

carrier disks TS1, TS2

tube lenses TUL1, TUL2

imaging objectives AO2, AO3

object translator OT

detection optics DL1, DL2

cameras KA1, KA2

analog-to-digital converters AD1, AD2

framegrabbers FG1, FG2

storages SP1, SP2

processor PR

mixed image MB

FIG. 10

Apart from elements that have already been mentioned,

tube lens TUL3 common to both beam paths

imaging objective AO4

detection optics DL3

FIG. 11

laser L1 with wavelength λ1

laser L2 with wavelength λ2

beam splitter ST6

condenser lens KOL3

microlens array MLA

polarizing beam splitter PST

pinhole array PH3

tube lens TUL4

quarter-wave plate PL

imaging objective AO5

detection optics DL4

dichroic beam splitter ST7

cameras KA1, KA2 with subsequent elements already described

What is claimed is:
 1. An arrangement for generating object images in amicroscope, comprising: means for recording at least two reflectedconfocal images of an object with distinguishable optical objectinformation with respect to image pixels and for storing them one afterthe other; and means for combining the recorded and digitized images ina pixel-exact manner and for storing a mixed image formed in this way;wherein a parallel confocal generation of raster images of the object iscarried out via different pinhole arrangements so that each initialimage of the object has a different confocal resolution.
 2. Thearrangement according to claim 1, wherein the mixed image is displayedon a picture screen or processed by image processing apparatus.
 3. Thearrangement according to claim 1, including means for generatingparallel confocal incident illumination bundles in or on the object. 4.The arrangement according to claim 1, wherein different pinholearrangements are used one after the other with respect to time for imagegeneration.
 5. The arrangement according to claim 1, wherein pinholearrangements are displaced for confocal scanning of the object.
 6. Thearrangement according to claim 1, wherein the object itself is displacedfor confocai scanning of the object.
 7. The arrangement according toclaim 1, wherein, in the case of a moving object, different andstationary pinhole arrangements are used for image recording of the sameobject area.
 8. The arrangement according to claim 1, with pinholearrangements arranged on a revolving strip.
 9. The arrangement accordingto claim 1, with different pinhole arrangements arranged on a rotatingdisk.
 10. The arrangement according to claim 1, with a white lightsource for object illumination.
 11. The arrangement according to claim1, comprising a light source, illumination optics, pinhole arrangement,imaging optics, object, wherein the light coming from the illuminatedobject is directed via the pinhole arrangement and a beam splitter inthe direction of optically after-magnifying detection optics which arearranged following the image processing means.
 12. The arrangementaccording to claim 1, wherein means are provided for correlating therecorded images with recording conditions.
 13. The arrangement accordingto claim 1, wherein synchronizing markers and sensors for detectionthereof are provided.
 14. The arrangement according to claim 1, whereinthe object is illuminated successively with different wavelengths. 15.The arrangement according to claim 1, wherein illumination is carriedout via the same or different pinhole arrangements.
 16. The arrangementaccording to claim 1, wherein at least one CCD camera is used for imagerecording.
 17. The arrangement according to claim 1, wherein at leastone TDI camera is used for image recording.
 18. The arrangementaccording to claim 1, wherein lasers of different wavelengths areprovided for illumination.
 19. The arrangement according to claim 1,wherein the image recording is carried out by a laser scanningmicroscope.
 20. The arrangement according to claim 1, wherein detectionand image recording are carried out successively with differentdetection wavelengths.
 21. The arrangement according to claim 1, whereina recording is carried out with different apertures of the illuminationsystem.
 22. The arrangement according to claim 1, wherein light sourcesare conventional, noncoherent light sources of different wavelengths andpredetermined bandwidth.
 23. The arrangement according to claim 1,wherein conventional light sources are high-power arc lamps.
 24. Thearrangement according to claim 1, wherein wavelengths for illuminationare extracted from a light source through suitable filers.
 25. Thearrangement according to claim 1, wherein a selection of wavelengths iscarried out by quickly changeable color filers in a form of switchingfilters or rotating sectored filter wheels.
 26. The arrangementaccording to claim 1, wherein light sources are laser light sources withdifferent wavelengths.
 27. The arrangement according to claim 1, inwhich a spatially parallel or temporally offset imaging of a lightsource in an object plane of an optical observation device is realizedby rhombus-shaped arrays or different, suitably arranged Nipkow typespiral patterns of pinhole elements.
 28. The arrangement according toclaim 1, in which structures of pinhole elements have a shape of aright-hand oriented or a left-hand oriented rhombic basic array and areused in a stationary manner in case of a moving object or areconstructed on a flexible revolving strip.
 29. The arrangement accordingto claim 1, in which parallel confocal scanning of the object plane inpairs is achieved by the displacement of the observation object incombination with a right-hand oriented or a left-hand orientedstationary rhombic basic array.
 30. The arrangement according to claim1, in which either pinhole arrays for illumination are likewise usedfunctionally for confocal image generation or, otherwise, the surfacereceivers have, in addition, a sensitivity structure which generatesconfocal characteristics in the image space.
 31. The arrangementaccording to claim 1, in which confocal characteristics of the surfacereceiver are achieved by masking diaphragms on a receiver, by surfaceelements of the receiver which are produced so as to be correspondinglysensitized, by an electronic sensitizing circuit or by a softwareselection control at the receiver or reception signal.
 32. Thearrangement according to claim 1, in which neutral,polarization-dependent or dichroically-splitting elements, chiefly inthe form of an optical cube or a rhomboid base body, are used to divideillumination and imaging bundles.
 33. The arrangement according to claim1, in which polarizing-optical splitters combined with quarter-waveplates are used in main beam paths to achieve a good splitting ofillumination and imaging.
 34. The arrangement according to claim 1, inwhich imaging elements have a high degree of optical correction foreliminating imaging errors, are outfitted in some components withzoom-optical characteristics, and an optical after-magnification isprovided in a detection beam path.
 35. The arrangement according toclaim 1, in which imaging elements are produced without optical stressesand two confocal images of an observation object are generated in twopolarization states and mixed by selective polarizing-optical paralleland vertical illumination.
 36. The arrangement according to claim 1, inwhich imaging elements have an adjustable transmission aperture, or in acase of dual-bundle arrangements, different transmission apertures, withsame magnification in order to generate and subsequently mix twoconfocal images of same observation object for two differenttransmission apertures.
 37. The arrangement according to claim 1, inwhich pinhole elements have a circular, square or rhombic basic shapeor, alternatively, have an annular shape of the respective basic figure.38. The arrangement according to claim 37, in which aright-hand-oriented or a left-hand oriented rhombic basic array on aflexible strip is used, by its revolution, for confocal scanning of anobject plane.
 39. An arrangement for generating object images in amicroscope, comprising: means for recording at least two reflectedconfocal images of a same object with distinguishable optical objectinformation with respect to image pixels and for storing them one afterthe other; and means for combining the recorded and digitized images ina pixel-exact manner, through subtraction; wherein a parallel confocalgeneration of raster images of the object is carried out via differentpinhole arrangements so that each initial image of the object has adifferent confocal resolution.
 40. A method for generating object imagesin a microscope, comprising the steps of: recording at least tworeflected confocal images of an object with distinguishable opticalobject information with respect to image pixels and storing them oneafter the other; and combining the recorded and digitized images in apixel-exact manner and the mixed image formed in this way is stored;wherein a parallel confocal generation of raster images of the object iscarried out via different pinhole arrangements so that each initialimage of the object has a different confocal resolution.
 41. The methodaccording to claim 40, in which electronic representatives of thedifferent optical confocal images are generated by digitization of areceiver signal.
 42. The method according to claim 40, in whichdifferent digitized confocal images are stored distinguishably instorages, which is controlled by synchronizing signals and an auxiliarysensor or is carried out by natural correlation of digitized confocalimages with respect to two receivers.
 43. The method according to claim40, wherein different digitized, distinguishably stored confocal imagesare combined to form a mixed image by fast image processors.
 44. Themethod according to claim 40, wherein an image recording isynchronizedby marker signals via an auxiliary sensor.
 45. The method according toclaim 40, characterized by subtraction operations Δ(P_(i″j″)) withelements P_(ij) and P_(i′j′) of measured confocal image matrices to formresultant elements P_(i″j″) of the image matrix in the mixed image. 46.A method for generating object images in a microscope, comprising thesteps of: recording at least two reflected confocal images of a sameobject with distinguishable optical object information with respect toimage pixels and storing them one after the other; and combining therecorded and digitized images in a pixel-exact manner, throughsubtraction; wherein a parallel confocal generation of raster images ofthe object is carried out via different pinhole arrangements so thateach initial image of the object has a different confocal resolution.